Tuberculosis FAQ

Tuberculosis Screening Tests

Tuberculosis skin test (TST) (formerly known as PPD)

  • Tubersol or Aplisol can be purchased through your medical supply chain.
  • Ten or 50 dose vials, once opened must be used within 28 days.
  • Requires skill to apply intradermally and read results properly.
  • Patient must have two office visits.
  • Sensitive test and inexpensive.
  • See the CDC TST poster.

Two-step skin testing

  • Two TSTs done within a 12-month period.
  • Apply the first test and read at 48 to 72 hours, and if test is 0 mm (negative), apply the second step one to three weeks after the first step was read.
  • If the first test result is ≥ 10mm (positive), do not apply the second step. Send for a two-view (PA and lateral) chest x-ray (CXR), then follow the CDC Latent Tuberculosis Infection (LTBI) Guide.

Blood assay for Mycobacterium tuberculosis

  • Excellent choice for screening people who may have received BCG vaccination (does not react to M. bovis BCG, only M. tuberculosis).
  • Check to see if covered by insurance, otherwise the test can be expensive.
  • Sensitive and specific for M. tuberculosis.

Positive Screening Results

  • Send for a two-view (PA and lateral) CXR.
  • If you have questions about the results of the test or CXR, hold the treatment until you call the Health Department.

Treatment of Latent Tuberculosis Infection

Do You Suspect Active Tuberculosis?

  • Report within 24 hours to the Health Department.
  • If you decide to order sputum cultures for tuberculosis, first read Order Sputum AFB for Providers.
  • The Health Department can facilitate sputum specimen testing by the Washington State Public Health Laboratory (PHL).

Assessing Your Agency or Facility for Tuberculosis Screening Needs